326 
It is to be regretted that churning tests were not made 
with these milks so that direct comparisons of the coeffi- 
cients in these tables and the efficiency of the churn could 
be made. We have, however, considerable data in regard 
to the behavior, when churned, of the milk from some of 
these cows. ‘There have been, during the past three years, 
a large number of churning tests with the milk of Jem, 
Ceres, Juno and Meg, which have shown that the value of 
their milk for butter is in the order named. The per cent. 
ratio of butter to fat in the milk for these cows has been 
Jem 100, Ceres 95, Juno 87.4, Meg 66. These numbers. 
represent the relative efficiency of the churn for milk from 
these cows when tested, and it is not probable that suffi- 
clent changes would occur to materially affect the relative 
value of the milks. 
For convenience of comparison, these values and the aver- 
age coefficients of viscosity, together with the total viscosity 
of the fat and serum of these milks, is presented below: 

TOTAL VISCOSITY DUE TO| Per cent. rela- 
———__~+-—____. .___--—___| tion of butter 
Solids not fat. to fat. 
COEFFICIENTS OF VISCOSITY. 


Fat./Solids not es Fat. 
Tam aaa 17.9! 19.8 93 183 100 
Genes Ptuabirs:, i321 20 | 74 | 178 95 
Dias tems 11.7 20.6 44 | 185 . 87.4 
Meg. nto: 9.1) 24 | 39 229 66. 
These figures indicate that a high coefficient for the fat. 
and a low one for the serum is most favorable to the eco- 
nomical production of butter. Itis quite generally conceded 
that milk containing large fat globules is more readily 
churned and yields a greater proportion of its fat as butter 
than does that with small globules. If, as seems probable, 
the variation in the coefficient of viscosity of the fateis due — 
to difference in the size of the globules, the relation between 
this coefficient and the efficiency of the churn is easily 
explained. 
The influence of the viscosity of the milk serum in dimin- 
ishing the efficiency of the churn has been confirmed by a 
number of experiments in which viscous substances were 
added to milk. Inthe example given below the same milk 
was used in each trial and all the samples were churned 
together in a test churn, the temperature being the same in 
each case. The mucilage added was a thin solution of gum 
arabic. The per cent. of butter is calculated for the quan- 
tity of milk used in each case. 
